Presentation for developing iPhone Applications

1. Introduction to iOS Programming
Dr. Thanisa Kruawaisayawan
www.imcinstitute.com

2. Get Started
• What are needed?
• Tools:
• Computer with Mac OSX (Intel based and Mountain Lion)
• Xcode 4.5.2
• iOS Developer Program (optional)
• Knowledge and Creativity
• Time
2

3. iOS Developer Programs
• iOS Developer Program ($99/year)
• To distribute apps on the App Store as an individual, sole proprietor, company or
organization (up to 100 registered devices)
• iOS Developer Enterprise Program ($299/year)
• To develop proprietary apps for internal distribution within your company,
organization, government entity or educational institution
• iOS Developer University Program (Free)
• To introduce iOS development into curriculum (up to 200 students)
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4. iOS > Application > Single View Application
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5. Product Name: HelloWorld
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6. Workspace Window of Xcode
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Source: http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iPhone101/Articles/01_CreatingProject.html

7. What Files Are In The Project?
• Source Files
• AppDelegate.h & AppDelegate.m
• ViewController.h & ViewController.m
• ViewController.xib
• Supporting Files
• HelloWorld-Info.plist
• main.m
7

8. iOS Application Life Cycle
Souce: http://developer.bada.com/article/A-Comparison-between-iOS-and-bada-Application-Development-Part1 8

9. main() => UIApplicationMain()
• The @autoreleasepool statement supports the Automatic Reference Counting
(ARC) system. ARC provides automatic object-lifetime management for your
app.
• The call to UIApplicationMain creates an instance of the
UIApplication and AppDelegate classes.
9

10. AppDelegate.m
10

11. Run and See Result
11

12. IB, XIB, and NIB Files
• Interface Builder (IB) is a GUI builder and object editor.
• Developer creates and configures objects, and then saves them to an archive.
• This archive or container is called “XIB” or “NIB”.
• We can have more than one xib/nib file in the project
ViewController.xib
12

13. XIB and NIB Files
• A XIB file is an XML representation of objects and their instance variables,
and it is compiled into a NIB file when application is built.
• XIB file is easier to work with, but NIB file is smaller and easier to parse.
• NIB file is copied into application bundle (a directory containing the
executable and any resources)
13

14. Application Bundle on the Simulator
• ~/Library/Application Support/iPhone Simulator/6.0/Applications
• Right Click at HelloWorld.app > Show Package Contents
chflags nohidden ~/Library/
14

15. iOS Simulator > Reset Content and Settings...
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16. XIB and NIB Files
16

17. ViewController.xib
• Drag Label onto screen
1
3
2
17

18. ViewController.xib
• Change text to Hello World and click Run
2
1
18

19. HelloWorld (Result)
19

20. HelloWorld2 (Result)
• When a user clicks a button “Say Hello”, “Hello World” is shown on the
screen.
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21. ViewController.xib
• Drag Round Rect Button onto screen and delete text of Label
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22. ViewController.h
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23. ViewController.m
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24. ViewController.xib
• Link label to Label
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25. ViewController.xib
• Link sayHello to Button
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26. Exercise: HelloWorld3
• Add another button to clear the message “Hello World”
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27. Assistant View
• Prior to Xcode 4, outlets and actions needed to be created in the view
controller’s header file before connecting them in Interface Builder (IB).
• Xcode 4’s assistant view gives us a much faster and more intuitive approach
that lets us create and connect outlets and actions simultaneously.
27

28. ViewController.xib to ViewController.h
• Control + Drag from an Object in IB to Header File
28

29. ViewController.xib
• Can “Say Hello” and “Clear” buttons call to the same action?
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30. Exercise: HelloWorld4
• Add text field to get the name of user to say “Hello “ user or say “Hello World”
when there is no name in the text field
The same
method for
two
buttons?
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31. Info Property List File
• Name: <Project Name>-Info.plist
• It contains a list of key-value pairs which is used to specify things such as
• Icon to display on the home screen
• Default language of the application
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32. HelloWorld-Info.plist
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33. App Icon and Launch Image for Your Application
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34. Prepare your files
Launch image
Display type App icon size Icon name Image name
size
Non-Retina
57 x 57 Icon.png 320 x 480 Default.png
display
Retina Display 114 x 114 Icon@2x.png 640 x 960 Default@2x.png
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35. HelloWorld Summary
• Drag “Icon.png” and “Icon@2x.png”
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36. HelloWorld-Info.plist
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37. HelloWorld Summary
• Drag “Default.png” and “Default@2x.png”
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38. How to Change iOS Simulator
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39. Code Completion
• Type initial character, then Pop-up Windows comes up automatically
• Keep typing to complete
• Press TAB to move to next Camel string
• Press Enter to complete that selection
• Press Arrow up/down to navigate
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40. Exercise (Results)
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41. Exercise: Sample of Data
• @"Ant" • @"Insect"
• @"Bee" • @"Jelly Fish"
• @"Cat" • @"Kingkong"
• @"Dog" • @"Leopard"
• @"Elephant" • @"Mountain Lion"
• @"Fish" • @"Nightingale"
• @"Goldfish" • @"Owl"
• @"Hippo" • @"Pig"
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42. Warning !!
• iOS programming doesn’t have garbage collection (unlike Mac OS
programming)
• So, we have to keep track of what we need.. what we no longer need.
42

43. Memory Management & String (Before iOS 5)
Scenario: create an NSString object
1. Create a pointer to NSString object
NSString *str1;
2. Allocate NSString object and set the pointer to object
str1 = [NSString alloc];
3. Initialize the object that the pointer points to
str1 = [str1 initWithFormat:@"Hello"];
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44. Memory Management & String (Before iOS 5)
1 Retain Count
str1 Hello NSString Obj
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45. Memory Management & String (Before iOS 5)
• To get current retain count :
[obj retainCount];
Retain Count
• To increase retain count :
[obj retain];
Hello NSString Obj
• To decrease retain count :
[obj release];
45

46. Memory Management & String (Before iOS 5)
There is another NSString object named str2 which points to a new object
with message “Ha ha”.
NSString *str2 = [[NSString alloc] initWithFormat:@"Ha ha"];
Then reallocate str1 to point to the same object as str2
str1 = str2;
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47. Memory Management & String (Before iOS 5)
1 Retain Count
This memory
space is wasted
Hello NSString Obj
str1
str2
Ha ha NSString Obj
Q: What is the retain count for the object with message “Ha ha”?
47

48. Memory Management & String (Before iOS 5)
0 Retain Count
• How can we do the proper set?
Hello
2 Retain Count
str1
str2 Ha ha NSString Obj
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49. Memory Management & Array (Before iOS 5)
1 Retain Count 1 Retain Count
Obj Array
49

50. Memory Management & Array (Before iOS 5)
2 Retain Count 1 Retain Count
Obj Array
50

51. Memory Management & Array (Before iOS 5)
2 Retain Count
1 Retain Count
Obj1
Array
1 Retain Count
Obj2
51

52. Memory Management & Array (Before iOS 5)
2 Retain Count
1 Retain Count
Obj1
Array
2 Retain Count
If we release array ?
Obj2
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53. Memory Management & Array (Before iOS 5)
2 Retain Count
RELEASE | -1 0 Retain Count
Obj1
Array
2 Retain Count
RELEASE | -1
Obj2
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54. Memory Management & Array (Before iOS 5)
1 Retain Count
0 Retain Count
Obj1
Array
1 Retain Count
Obj2
54

55. Memory Management & Array (Before iOS 5)
In many cases
• You want to have an array.
• You add objects to the array.
• When the array is destroyed, you want the members to be destroyed as well..
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56. Memory Management & Array (Before iOS 5)
1 Retain Count 1 Retain Count
Obj Array
56

57. Memory Management & Array (Before iOS 5)
2 Retain Count 1 Retain Count
Obj Array
RELEASE | -1
57

58. Memory Management & Array (Before iOS 5)
1 Retain Count 1 Retain Count
Obj Array
58

59. Memory Management & Array (Before iOS 5)
1 Retain Count
1 Retain Count
Obj1
Array
1 Retain Count
Obj2
59

60. Memory Management & Array (Before iOS 5)
1 Retain Count
1 Retain Count
Obj1
Array
2 Retain Count
Obj2 RELEASE | -1
60

61. Memory Management & Array (Before iOS 5)
1 Retain Count
1 Retain Count
Obj1
Array
1 Retain Count
If we release array ?
Obj2
61

62. Memory Management & Array (Before iOS 5)
0 Retain Count
RELEASE | -1 0 Retain Count
Obj1
Array
0 Retain Count
RELEASE | -1
Obj2
62

63. Memory Management & Array (Before iOS 5)
0 Retain Count
0 Retain Count
Obj1
Array
0 Retain Count
Obj2
63

64. AutoReleasePool
• What method returns object in autorelease pool ?
NSXyz *a = [NSXyz xyzWith...];
• This is called “Convenience method”.
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65. @property (Before Xcode 4.2)
@property (attributes) type name;
• The attributes are divided into groups and can take the following values :
• Access type
• readwrite (default) : will generate getter and setter
• readonly : will only generate getter
• Memory management
• assign (default) : setter will not retain memory, just assign pointer
• retain : setter will retain memory
• copy : setter will copy memory zone (thus calling alloc and thus retain the new copy)
• Thread management
• nonatomic : if nonatomic is not mentioned, the setter will be thread-safe by default
(synchronized method)
65

66. @synthesize
• @synthesize name;
• Example: @synthesize str1;
-(NSString *) str1
{
return str1;
}
-(void) setStr1:(NSString *) str2
{
if (str1 != str2)
{
[str2 retain];
[str1 release]; [ str1 release];
str1 = str2; str1 = [str2 copy]; str1 = str2;
}
} retain copy assign
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67. Some New Features Starting from Xcode 4.2
• Automatic Reference Counting (ARC)
• Default Compiler for iOS development
• Xcode 4.5 : LLVM 4.1
• Xcode 4.4 : LLVM 4.0
• Xcode 4.3 : LLVM 3.1
• Xcode 4.2 : LLVM (Low Level Virtual Machine) 3.0
• Xcode 4.1 : LLVM-GCC
• Xcode 4.0 : GCC (GNU Compiler Collection)
• Storyboarding
67

68. Automatic Reference Counting (ARC)
Source: http://developer.apple.com/library/ios/#releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
68

69. ARC
• ARC is a compiler feature that provides automatic memory management of
Objective-C objects. ARC works by adding code at compile time to ensure
that objects live as long as necessary, but no longer. Conceptually, it follows
the same memory management conventions as manual reference counting by
adding the appropriate memory management calls for you.
• LLVM 3.0 compiler that Apple started shipping with iOS 5 is so smart that it
will release objects for us, using ARC. That means no more dealloc methods,
and no more worrying about calling release or autorelease.
• ARC applies to only Objective-C objects, not to Core Foundation objects or
to memory allocated with malloc.
69

70. Manual Reference Counting
Source: http://teamtreehouse.com/library/ios-5-foundations/automatic-reference-counting/getting-started/play
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71. Automatic Reference Counting
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72. Comparing Manual and Automatic Reference Counting
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73. Strong and Weak properties
• @property (retain) MyClass *myObject;
=> @property (strong) MyClass *myObject;
• @property (assign) MyClass *myObject;
=> @property (weak) MyClass *myObject;
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74. Convert Old Codes to Objective-C ARC Codes
• Open HelloWorld project developed in Xcode 4.0
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75. Changes in HelloWorldAppDelegate.h
After Converting Before Converting
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76. Changes in HelloWorldAppDelegate.m
After Converting Before Converting
76

77. Changes in main.m
After Converting Before Converting
77

78. Strong property
NSString *firstName = textField.text;
Source: http://www.raywenderlich.com/5677/beginning-arc-in-ios-5-part-1 78

79. Weak property
__weak NSString *weakName = textField.text;
79

80. Storyboarding
• In Xcode 4.2, the Interface Builder user interface for iOS applications is based
on the storyboarding of view controllers.
• Storyboarding enables you to use Interface Builder to specify not only all the
screens in your application, but the transitions between them and the controls
used to trigger the transitions.
• Thus you can lay out every possible path through your application graphically,
greatly reducing the amount of code you need to write for a complex
multiscreen application.
80

81. New a Single View Application > HelloWorld_Storyboard
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82. MainStoryboard.storyboard
82

83. MainStoryboard.storyboard
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84. References
• Boonyanit Mathayomchan, Ph.D., “iPhone Application
Development (BASIC)”, 2011
• Chotipat Pornavalai, iPhone Basic #1, Mini Master of iOS
Application #1
• Dave Mark, et.al, “Beginning iOS5 Development: Exploring the iOS
SDK”, 2012
• Joe Conway & Aaron Hillegass, “iPhone Programming: The Big
Nerd Ranch Guide”, 2010
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